1. Technical Field
The present invention relates to a liquid crystal display device and an electronic apparatus.
2. Related Art
A method for controlling alignment of liquid crystal molecules by applying an electric field to a liquid crystal layer in a direction of a substrate surface is known (hereinafter referred to as a “lateral electric field method”). Examples of the lateral electric field method include an IPS (In-Plane Switching) method and an FFS (Fringe-Field Switching) method. Japanese Unexamined Patent Application Publication Nos. 2003-233083 and 2007-264231 disclose liquid crystal display devices employing the FFS methods, and in particular, disclose methods for attaining wide view angles using pixel electrodes having multi domain configurations.
Referring to FIG. 9, each of the liquid crystal display devices disclosed in Japanese Unexamined Patent Application Publication Nos. 2003-233083 and 2007-264231 includes slit electrodes each of which is constituted by bending a pixel electrode at the center thereof so as to have a V shape in a plan view. Each of the slit electrodes includes a first slit electrode which is an upper-half portion of the pixel electrode and a second slit electrode which is a lower-half portion of the pixel electrode. The first and second slit electrodes are arranged symmetrically with respect to an arrangement axis AX extending in a horizontal direction. A rubbing direction of an alignment film (alignment controlling direction) is substantially orthogonal to the arrangement axis AX, and an optical axis of a polarizing plate (for example, a transmission axis) is substantially parallel to the rubbing direction of the alignment film.
In the vicinity of the slit electrodes, lateral electric fields are generated in directions orthogonal to directions in which the slit electrodes extend. Liquid crystal molecules rotate within a substrate horizontal plane from the rubbing direction to directions of the electric fields. In a first display region including the first slit electrode, the direction of the electric field intersects with the rubbing direction so as to make an acute angle with the rubbing direction in a counterclockwise direction, and therefore, a liquid crystal molecule corresponding to the first slit electrode rotates in the counterclockwise direction. On the other hand, in a second display region including the second slit electrode, the direction of the electric field intersects with the rubbing direction so as to make an acute angle with the rubbing direction in a clockwise direction, and therefore, a liquid crystal molecule corresponding to the second slit electrode rotates in the clockwise direction. Since the rotation direction of the liquid crystal molecule of the first slit electrode is different from the rotation direction of the liquid crystal molecule of the second slit electrode, view-angle compensation is performed within a plane of the single pixel electrode. Accordingly, display with wide view angle is attained.
In FIG. 9, it is an ideal that the optical axis of the polarizing plate is parallel to the rubbing direction of the alignment film. However, in some cases, the rubbing direction could be tilted with respect to the optical axis of the polarizing plate depending on alignment accuracy of a rubbing device, for example. For example, as shown in FIG. 9, when the rubbing direction is tilted with respect to the optical axis of the polarizing plate by an angle θR in the clockwise direction, the liquid crystal molecule included in the first display region rotates in the direction of the electric field across the optical axis of the polarizing plate. Therefore, when the liquid crystal molecule is arranged in parallel to the optical axis of the polarizing plate, a dark image is displayed, that is, brightness of the image is deteriorated. On the other hand, since the liquid crystal molecule included in the second display region does not rotate across the optical axis of the polarizing plate, brightness of an image increases in proportion to a magnitude of an applied voltage. Accordingly, the brightness of the first display region becomes different from the brightness of the second display region. Therefore, in particular, in a case where halftone display is performed, unevenness of brightness could be recognized. This problem becomes larger as sizes of pixel electrodes become larger in accordance with increase of a size of the liquid crystal display device.
Note that although the liquid crystal display device employing the FFS method is described with reference to FIG. 9, the problem described above also arises in liquid crystal display devices employing the IPS methods. An example of the liquid crystal display devices employing the IPS methods includes pixel electrodes and a common electrode which are constituted by a plurality of slit electrodes (interdigital electrodes) arranged so that the pixel electrodes are meshed with the common electrode. Therefore, by bending the individual slit electrodes of the pixel electrodes and the common electrode into V shapes, a wide view angle is attained. However, in this case also, the problem described above with reference to FIG. 9 arises due to displacement between the rubbing direction and the optical axis of the polarizing plate.